CA1195971A - Method of preparing high silica zeolites with control of zeolite morphology - Google Patents
Method of preparing high silica zeolites with control of zeolite morphologyInfo
- Publication number
- CA1195971A CA1195971A CA000426581A CA426581A CA1195971A CA 1195971 A CA1195971 A CA 1195971A CA 000426581 A CA000426581 A CA 000426581A CA 426581 A CA426581 A CA 426581A CA 1195971 A CA1195971 A CA 1195971A
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- Prior art keywords
- zsm
- silica
- zeolite
- final
- zeolites
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B37/00—Compounds having molecular sieve properties but not having base-exchange properties
- C01B37/02—Crystalline silica-polymorphs, e.g. silicalites dealuminated aluminosilicate zeolites
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/03—Catalysts comprising molecular sieves not having base-exchange properties
- B01J29/035—Microporous crystalline materials not having base exchange properties, such as silica polymorphs, e.g. silicalites
Abstract
METHOD OF PREPARING HIGH SILICA ZEOLITES
WITH CONTROL OF ZEOLITE MORPHOLOGY
Abstract This invention is concerned with an improved process for crystallizing high silica zeolites and, more particularly, is concerned with the preparation of high silica zeolites having a silica-to-alumina ratio of greater than 70, up to and approaching infinity, by control of the pH so as to obtain zeolitic compositions of a varying morphology depending on the final pH of the reaction medium.
WITH CONTROL OF ZEOLITE MORPHOLOGY
Abstract This invention is concerned with an improved process for crystallizing high silica zeolites and, more particularly, is concerned with the preparation of high silica zeolites having a silica-to-alumina ratio of greater than 70, up to and approaching infinity, by control of the pH so as to obtain zeolitic compositions of a varying morphology depending on the final pH of the reaction medium.
Description
MET~D OF PREPARING HIGH SILICA ZEOLITES
WITH CON~OL OF ZEOLITE MOR ~ LOGY
This invention is concerned with the crystallization of high silica zeolites and, more particularly, is concerned with the S preparation of high silica zeolites having a silica-to-alumlna ratio of greater than 709 Up to and approaching in~inity9 by control of the reaction medium pH so as to obtain zeolitic compositions of a varying morphology depending on the final pH of the reaction medium.
High silica zeolites are extremely well known in the art and ~ have been the subject of much attention in both the patent and technical literature. It has now been discovered that the norphology of the crystals produced ~rom a ~orming solution varies depending upon the final pH of the reaction medium. As is well known in the art of the synthesis o~ zeolites, it is extremely difficult to control the pH
S o~ the _eolite forming solution and, in fact? it is extremely di~ficult eYen to measure the pH during cryst~ tion since cryst~lli7ation is usually carried out in closed vessels under autogeneous pressure such that exact measurements are not practical.
It is known in the art that there is a certain pH range over which %SM-5 type zeolites can be prepared and, in this connection, Grose e~ al, U.S. Patent ~,061,724, issued December 6, 1977l discloses a pH range of 10-140 However this patent does not teach that the morphology of the resulting crystals is dependent on the pH of the reaction medium~ It is also known that the pH is difficult to control and that it varies during the course of crystallization.
This invention relates to an improved process for carrying out the crystalli7ation of zeolites, and especially high silica ZSM-5 type zeolites, using the same reactants as have previously been described in various patents and technical articles; but carrying out the cryst~ 7~tion in the presence of a buffer such that the pH of the reaction mixture is maintained within the range o~ 9.5 to 12. In this manner, the morphology of the zeolite products produced can be controlled depending upon whether a low, intermediate, or high final reaction mixture pH is utilized.
It has long been recognized in the synthesis o~ various crystalline aluminosilicates of the low silica type that complexing agents such as phosphates, arsenates9 tartrates, citrates, ethylenediaminetetraacetate~ etc also can act as a buf~er. The use of these materials has been primarily directed to those situations where it was desired to increase the silica-to alumina ratio of the zeolite by complexing the alumina. Thus, procedures of this type are disclosed in U~S. Patent 3,8~69801; U.S. Patent 4~20~7869; as well as in an article entitled "Influence of Phosphate and Other Complexing Agents on the Crystalli~ation of ~eolites," appearing in Molecular Sieves, Soc. of Chem. Industry, London, pp. 85, etO seq. (1967).
All of the above three publications have ~or a common goal the use of a material which complexes the aluminum such that a zeolitic product is obtained which has a higher silica-to-alumina ratio than that which would normally be obtained from the same reaction medium in the absence of such complexing agents. As indicated earlier~ certain of the complexing agents are also buffers, but they are used in amounts such that their primary objective is to complex all or a portion of the aluminum, thereby raising the silica~to-alumina ratio of the resulting zeolite. In the above referred to article, as well as in U.SO Patent 3~386,8013 low silica zeolites are dealt with such that the complexing agent added does not complex all the aluminum due to equilibrium considerations. On the other hand9 U.S. Patent 4,0~8,605, which is directed towards high silica to-alumina ratio zeolites, discloses that the function of the complexing agent is indeed to complex substantially all the available ~luminum which9 of course, also raises the silica-to-alumina ratio of the final crystalline productO References such as U.S. Patent 3,949,059 teach the use of bu~fers ln the cryst~ll;7ation of a low silica zeolite. The novel process of this invention is not concerned with the use of complexing agents which may additionally be buffers in amounts such that they complex with aluminum and raise the silica-to-alumina ratio o~ the zeolitic product nor is the novel process herein conce m ed with low silica ~eolites. In other words9 in the novel process of this 3 ~ 7~
invention, a buffer is used in an amount such that the silica~to-alumina ratio o~ the product is substantially una~fected, i.e., it would have the same high silica-to-alumina ratio whether or not a buffer were used.
The novel process of this invention is based on the discovery that the pH of the reaction mixture is of paramount importance in eskablishing the ~orphology of the high silica crystalline zeolite products, pre~erably of the ~SM~5 type. It has been discovered that twinned short pris~atic ZSM-5 crystals frequently with near spherulitic morphology can be obtained when final pH values of the reaction mixture are above 12 and up to 12.5. On the other hand9 if the final pH is in the range o~ 10 10.5, rod type ZSM 5 can be crystallized. An intermediate type morphology was found in the pH
range of 11-12. Thus, depending on what type of morphology is desired with regard to the ZSM-5 type zeolites9 the final pH should be controlled within the general ranges above set forth.
As has heretofore been stated, it is well known in the art that the pH of a reaction mixture in zeolite synthesis cannot be carefully controlled and that pH does vary over fairly wide ranges during the steps of gel preparation, aging, and during the course of crystallization. The novel process of this invention minimizes the variation in pH by using a buffer which would effectively control the pH to any desired value within the ranges above set forth~ thereby greatly facilitating the cryst~lli7ation of a zeolite of a particular morphology.
A particularly preferred embodiment of this invention resides in controlling the final pH within the rangc o~ 10-10.5 in order to obtain ZSM-~ having rod-type morphology.
The buffer utilized is not narrowly critical, and any buffer capable of stabilizing the pH in this range at 200C in a pressure vessel can facilitate cryst~lli7ation of the desired morphology.
Typical bu~ers would include phosphates, tartrates, citrates~
oxalates, ethylenediaminetetraacetate9 acetate and carbonate~
_ 4 ~ 7~
The amount o~ buffer which is used is determined by many factors, including the particular nature of the buf~er itsel~, as well as the final pH which is desired. In general, though7 it can be stated that the bu~fer has to be used in sufficient amounts such that it does act as a buf~er in order to stabilize the pH.
In general, it can be stated that the amount of buffer used is such that there is present in the reaction medium 0.1 to about 0.35 equivalents of buffer per mol of silicaO Greater amounts of bu Mer can be used, but the increased salt concentration reduces the rate o~
cryst~ll;7ation~ As has heretofore been stated, the novel process of this invention resides in controlling the pH during cryst~ ation of a high silica zeolite. The method used to control the pH is by the use of a buffer. As has also been indicated9 it is difficult to measure the pH during crystallization so that a very ef~ective correlation has been made by measuring the final pH, iOe., the pH
after cryst~ll;7ationO It is precisely this final pH which has been correl~ted with the morphology of the high silica zeolites which are produced.
The novel process of this invention is concerned with the synthesis of high silica-containing zeolites, and this expression is intended to define a crystalline structure which has a silica-to-alumina ratio greater than 70 and9 more preferably, greater than 500, up to and including those highly sil;ceolls materials where the silica-to alum;na ratio is in~inity or as reasonably close to in~inity as practically possible.
This latter group of highly siliceous ma-terials is exemplified by U.S. Patents 3,941,871; 4,061,724; 4,073,865;
4,104,~94; wherein the materials are prepared from reaction solutions which involve no deliberate addition of aluminum. However, trace quantities of aluminum are usually present due to the impurity of the reactants. It is also to be understood that the expression "high silica-containing zeolitel' also specifically includes those materials which have other metals besides silica and/or alumina associated therewith, such as boron9 iron, chromium, etc.
~5~73~
Particularly pre~erred high silica zeolites which can be prepared in accordance with the present invention are those of the ZSM-5 type. ZSM-5 type zeolites are those having a Constraint Index within the approximate range of l to 120 ZSM-5 type zeolites are exemplified by ZSM-5, ~5M-ll, ZSM 12, ZSM-35, ZSM-38, and ZSM-48 and other similar materials. U.S. Patent 3~702J8~6 describes and claims ZSM-5.
ZSM-ll is more particularly described in U.S. Patent 3,709,979.
ZSM-12 is more particularly described in U.50 Patent 3,8~29449.
ZSM-35 is more particularly described in U.S. Patent 4,016,245.
ZSM-38 is more particularly described in U.S. Patent 4,0~6,85g-ZSM-48 is more particularly described in U.S. Patent 4,375,5~3.
As is set ~orth in the above-identified U.S. patents~ the zeolites o~ this invention are prepared from a forming solution containing water9 a source of quaternary ammonium cations7 an alkali metal, silica, with or without added alumina and with or without the presence of additional metalsO As is known in the art, the forming solution is held at elevated temperatures and pressures until the crystals are formed and therea~ter the zeolite crystals are removed.
The novel process o~ this invention resides in using the exact forming solutions which have previously been taught for the preparation of zeolites such as ZSM-5 and adding therewith a buf~ering agent so as to have a final pH within the range of 9.5-12.5 depending on the particular crystal morphology which is desired~
The ~ollowing examples will illustrate the novel pxocess of this invention using various buffering agents. In all cases7 cQ110i~1 silica sol identified as Ludox LS containing 30 weight percent silica was used for cryst~11;7ations. The molar ratio of silica to tetrapropylammonium bromide (TPA8r) was held nearly constant 7~
at 19.8 to 19.9 and that of sodium hydroxide to TPABr ~as held ` constant at 3.05. Percent crystallinity is based on X ray comparison with a highly crystalline reference sample.
Generally, the reaction mixtures were prepared by dissolving tetrapropylammonium bromide, alkali hydroxide and a particular salt, water, and adding (Ludox ~silica sol to this solution.
All cryst~lli7~tions were carried out in non-stirred pressure vessels equipped with Teflo ~liners and heated by immersion in a constant temperature silicone oil bath~
~rief Description of the Figures Figures la and lb are scanning electron-micrographs of the product of Examples 3 and 4~ respectively.
Figures 2a, 2b, and 2c are scanning electron-micrographs of the product of Examples 6, 7, and ~ respectively.
S Fi9ure 3 is a scanning electron-micrograph of the product of Example 10.
Figures 4a, 4b, and ~c are scanning electron-micrographs nf the product of Examples 12, 13, and 14, respectively.
Figure 5 is a scanning electron-micrograph of the product of a o Example 15.
Figure 6 is a scanning electron-micrograph of the product of Example 16.
Figure 7 is a scanning electron-micrograph of the product of Example 17.
~s~ Figures 8a and 8b are scanning electron-micrographs of the products of Examples 19 and 20, respectivelyO
Figures 9a, 9b, and 9c are scanning electron~micrographs of the products of Examples 22, 23, and 24~ respectively~
Figure 10 is a scanning electron-micrograph of the product of 3 Example 25.
Figure 11 is a scanning electron-micrograph of the product of Example 27a.
Figure 12 is a scanning electron-micrograph of the product of Example 27b.
Figure 13 is a scanning electron-micrograph of the product of Example 27c.
Crys~11;7ation of High Silica ZSM-5 in the Presence of Phosphate As has been indicated previously, phosphate has been known to complex aluminum and its complexing and buffering properties cause cryst~lli7ation of zeulites with higher silica-to-alumina ratios than obtained from a similar phosphate-free reaction medium.
The reaction mixture of Example 1 was prepared using 4.2 mols of (NH4)2HP04 per mol of tetrapropylammonium bromide (TPABr) in an attempt to complex alumina impurities and buffer the sodium hydroxide added. The amount of buffer added was equivalent ko 0.42 equivalents of HPO-4 per equivalent of silica. The amount of (NH4)2HP04 was lowered in Examples 2 and 3 to amounts ranging from 0.21 to 0.14 equivalents per mol of silica, respectively.
Finally, am~onia was added in Example 4 to obtain an eqllirol~r concentration of (NH4)2HP04 and N~ . The eQuivalent amount of HPO 4 per mole of silica was 0.14. The reaction mixtures that crystallized completely had the hishest pH, the products having practically identical sorption capacities as will be shown in Table 1.
Cryst~11;7~tion of Hi~h Silica ZSM-5 in the Presenoe o~ Tartrate9 Citrate and Oxalate The reaction mixtures containing 2.1 mols of ammonium salts of tartaric, citric, and oxalic acid per mol of TPABr crystallized incompletely or not at all (Examples 5, 9 and 11). This amount is equivalent to 0.21 equivalents of tartrate and oxalate (Examples 5 and 11) and 0.32 equivalents of citrate (Example 9) per mol of silica.
Common to all ~hree is very low p~ of the f;nal solution. When the amount of tartaric acid was reduced, the crystallinity of the products improved. Simultaneously, the crystals became less elongated ~see - 8 ~ 5~37~
Figure 2). When only hal~ the amount of ammonium citrate was used (Example 10), citrate to TPABr equals 1.05, equivalents of citrate to moles of silica equals 0~16 which is similar to the reaction mixture o~ Example 6, and ayain, a good ZSM-5 was obtained. However, in the citrate mixture~ both the citric acid and ammonia were deereased, thereby the pH ~or Figure 2b was higher than that ~or Figure 3~
When the amount of ammonium oxalate was reduced (Examples 12-13), the resulting products were similar to those obtained with tartrate, i.e., see Table 2 and Figure 4~ Sodium oxalate, instead o~
ammonium oxalate, was used in Example 1~ resulting in a higher pH and more crys~ll77ation of quartz~ Results are shown in Table 2.
Cryst~ ation of High Silica ZSM 5 in the Presence of Gluconate~ Salicylate and EDTA
Reaction mixtures were prepared containing 2.1 moles of gluconate or salicylate per mol of TPABr which is equivalent to .105 equivalents o~ bu~fer per mol of silica, and these had pH values above 11 attributable to the weaker acids. The gluconate (Fxample 15) ~Pc~rosed during crys~lli7ation, and the carbon formed was burned of~ by calcination at 550C be~ore analytical tests were carried out.
The crystals obtained with gluconate are highly twinned (see Figure 5).
Less twinning is observed in the product of Example 16 obtained in the presence of salicylic acid (see Figure 6) Crystals similar to those obtained when phosphate was present in the reaction mixtures, i.e., see Figure 1, crystallized in the presence o~ ethylenediaminetetraacetate (EDTA~ (Figures 7a and b~
~ultiple twinning resulting in rudimentary spherulites can also be seen in Figure 7b. The material has a high crystallinity which is also evident from the high n-hexane and low cyclohexane sorp~ion capacitiesO See Table 3.
-~ 9~ s~
EXQMPLES 18~25 Crystallization in the Presence of Acetate and Carbonate Ammonium acetate was used in Examples 18-21. With 4.2 moles of acetate/mole of TPABr which is equivalent to ~21 equivalents of buffer per mol of silica9 th crystallization was still incomplete after 495 hours. With less ammonium acetate, 3.2 moles/mol of TPAer (Q.16 equivalents per mol of SiO2), somewhat more rapid crystallization was observed, although it was still incomplete a~ter 163 hours (see Example 19). The scanning electron micrograph shows the same rod-shaped crystals as observed previously from low pH
reaction mixtures, e.g., with tartrate (see Example 6, Figure 2a) and oxalate (Example 12, Figure 4a) At 2.1 moles of ammonium acetate/mole o~ TPABr (~105 equivalents of ammonium acetate per mole of SiO20), a well crystallized product was obtained in 65 hours (Example 20). The ratio of width/length of these crystals is considerably incre~sed, and some 90 twinning is observed (see Figure 8b). When the amount of NaOH wzs reduced (see Example 21), a material similar to that of Example 19 (Figure 8a) was obtained~
~mmonium carbonate was used in the remaining examples of Table 4 (Examples 2~25). At 3.2 moles of ammonium carbonate per mole of TPABr (0.16 equivalents of HC03 per mole o~ silica), rod-shaped crystals were obtained simultaneously with more stubby and 90 twinned crystals (see Figure 9a). Surface etching, caused by redissolution and beginning recrystallization indicates that the cryst~lli7ation was completed considerab~y sooner than after 122 hours when the reaction was terminated.
Considerably shorter crystals formed at carbonate/TPABr of
WITH CON~OL OF ZEOLITE MOR ~ LOGY
This invention is concerned with the crystallization of high silica zeolites and, more particularly, is concerned with the S preparation of high silica zeolites having a silica-to-alumlna ratio of greater than 709 Up to and approaching in~inity9 by control of the reaction medium pH so as to obtain zeolitic compositions of a varying morphology depending on the final pH of the reaction medium.
High silica zeolites are extremely well known in the art and ~ have been the subject of much attention in both the patent and technical literature. It has now been discovered that the norphology of the crystals produced ~rom a ~orming solution varies depending upon the final pH of the reaction medium. As is well known in the art of the synthesis o~ zeolites, it is extremely difficult to control the pH
S o~ the _eolite forming solution and, in fact? it is extremely di~ficult eYen to measure the pH during cryst~ tion since cryst~lli7ation is usually carried out in closed vessels under autogeneous pressure such that exact measurements are not practical.
It is known in the art that there is a certain pH range over which %SM-5 type zeolites can be prepared and, in this connection, Grose e~ al, U.S. Patent ~,061,724, issued December 6, 1977l discloses a pH range of 10-140 However this patent does not teach that the morphology of the resulting crystals is dependent on the pH of the reaction medium~ It is also known that the pH is difficult to control and that it varies during the course of crystallization.
This invention relates to an improved process for carrying out the crystalli7ation of zeolites, and especially high silica ZSM-5 type zeolites, using the same reactants as have previously been described in various patents and technical articles; but carrying out the cryst~ 7~tion in the presence of a buffer such that the pH of the reaction mixture is maintained within the range o~ 9.5 to 12. In this manner, the morphology of the zeolite products produced can be controlled depending upon whether a low, intermediate, or high final reaction mixture pH is utilized.
It has long been recognized in the synthesis o~ various crystalline aluminosilicates of the low silica type that complexing agents such as phosphates, arsenates9 tartrates, citrates, ethylenediaminetetraacetate~ etc also can act as a buf~er. The use of these materials has been primarily directed to those situations where it was desired to increase the silica-to alumina ratio of the zeolite by complexing the alumina. Thus, procedures of this type are disclosed in U~S. Patent 3,8~69801; U.S. Patent 4~20~7869; as well as in an article entitled "Influence of Phosphate and Other Complexing Agents on the Crystalli~ation of ~eolites," appearing in Molecular Sieves, Soc. of Chem. Industry, London, pp. 85, etO seq. (1967).
All of the above three publications have ~or a common goal the use of a material which complexes the aluminum such that a zeolitic product is obtained which has a higher silica-to-alumina ratio than that which would normally be obtained from the same reaction medium in the absence of such complexing agents. As indicated earlier~ certain of the complexing agents are also buffers, but they are used in amounts such that their primary objective is to complex all or a portion of the aluminum, thereby raising the silica~to-alumina ratio of the resulting zeolite. In the above referred to article, as well as in U.SO Patent 3~386,8013 low silica zeolites are dealt with such that the complexing agent added does not complex all the aluminum due to equilibrium considerations. On the other hand9 U.S. Patent 4,0~8,605, which is directed towards high silica to-alumina ratio zeolites, discloses that the function of the complexing agent is indeed to complex substantially all the available ~luminum which9 of course, also raises the silica-to-alumina ratio of the final crystalline productO References such as U.S. Patent 3,949,059 teach the use of bu~fers ln the cryst~ll;7ation of a low silica zeolite. The novel process of this invention is not concerned with the use of complexing agents which may additionally be buffers in amounts such that they complex with aluminum and raise the silica-to-alumina ratio o~ the zeolitic product nor is the novel process herein conce m ed with low silica ~eolites. In other words9 in the novel process of this 3 ~ 7~
invention, a buffer is used in an amount such that the silica~to-alumina ratio o~ the product is substantially una~fected, i.e., it would have the same high silica-to-alumina ratio whether or not a buffer were used.
The novel process of this invention is based on the discovery that the pH of the reaction mixture is of paramount importance in eskablishing the ~orphology of the high silica crystalline zeolite products, pre~erably of the ~SM~5 type. It has been discovered that twinned short pris~atic ZSM-5 crystals frequently with near spherulitic morphology can be obtained when final pH values of the reaction mixture are above 12 and up to 12.5. On the other hand9 if the final pH is in the range o~ 10 10.5, rod type ZSM 5 can be crystallized. An intermediate type morphology was found in the pH
range of 11-12. Thus, depending on what type of morphology is desired with regard to the ZSM-5 type zeolites9 the final pH should be controlled within the general ranges above set forth.
As has heretofore been stated, it is well known in the art that the pH of a reaction mixture in zeolite synthesis cannot be carefully controlled and that pH does vary over fairly wide ranges during the steps of gel preparation, aging, and during the course of crystallization. The novel process of this invention minimizes the variation in pH by using a buffer which would effectively control the pH to any desired value within the ranges above set forth~ thereby greatly facilitating the cryst~lli7ation of a zeolite of a particular morphology.
A particularly preferred embodiment of this invention resides in controlling the final pH within the rangc o~ 10-10.5 in order to obtain ZSM-~ having rod-type morphology.
The buffer utilized is not narrowly critical, and any buffer capable of stabilizing the pH in this range at 200C in a pressure vessel can facilitate cryst~lli7ation of the desired morphology.
Typical bu~ers would include phosphates, tartrates, citrates~
oxalates, ethylenediaminetetraacetate9 acetate and carbonate~
_ 4 ~ 7~
The amount o~ buffer which is used is determined by many factors, including the particular nature of the buf~er itsel~, as well as the final pH which is desired. In general, though7 it can be stated that the bu~fer has to be used in sufficient amounts such that it does act as a buf~er in order to stabilize the pH.
In general, it can be stated that the amount of buffer used is such that there is present in the reaction medium 0.1 to about 0.35 equivalents of buffer per mol of silicaO Greater amounts of bu Mer can be used, but the increased salt concentration reduces the rate o~
cryst~ll;7ation~ As has heretofore been stated, the novel process of this invention resides in controlling the pH during cryst~ ation of a high silica zeolite. The method used to control the pH is by the use of a buffer. As has also been indicated9 it is difficult to measure the pH during crystallization so that a very ef~ective correlation has been made by measuring the final pH, iOe., the pH
after cryst~ll;7ationO It is precisely this final pH which has been correl~ted with the morphology of the high silica zeolites which are produced.
The novel process of this invention is concerned with the synthesis of high silica-containing zeolites, and this expression is intended to define a crystalline structure which has a silica-to-alumina ratio greater than 70 and9 more preferably, greater than 500, up to and including those highly sil;ceolls materials where the silica-to alum;na ratio is in~inity or as reasonably close to in~inity as practically possible.
This latter group of highly siliceous ma-terials is exemplified by U.S. Patents 3,941,871; 4,061,724; 4,073,865;
4,104,~94; wherein the materials are prepared from reaction solutions which involve no deliberate addition of aluminum. However, trace quantities of aluminum are usually present due to the impurity of the reactants. It is also to be understood that the expression "high silica-containing zeolitel' also specifically includes those materials which have other metals besides silica and/or alumina associated therewith, such as boron9 iron, chromium, etc.
~5~73~
Particularly pre~erred high silica zeolites which can be prepared in accordance with the present invention are those of the ZSM-5 type. ZSM-5 type zeolites are those having a Constraint Index within the approximate range of l to 120 ZSM-5 type zeolites are exemplified by ZSM-5, ~5M-ll, ZSM 12, ZSM-35, ZSM-38, and ZSM-48 and other similar materials. U.S. Patent 3~702J8~6 describes and claims ZSM-5.
ZSM-ll is more particularly described in U.S. Patent 3,709,979.
ZSM-12 is more particularly described in U.50 Patent 3,8~29449.
ZSM-35 is more particularly described in U.S. Patent 4,016,245.
ZSM-38 is more particularly described in U.S. Patent 4,0~6,85g-ZSM-48 is more particularly described in U.S. Patent 4,375,5~3.
As is set ~orth in the above-identified U.S. patents~ the zeolites o~ this invention are prepared from a forming solution containing water9 a source of quaternary ammonium cations7 an alkali metal, silica, with or without added alumina and with or without the presence of additional metalsO As is known in the art, the forming solution is held at elevated temperatures and pressures until the crystals are formed and therea~ter the zeolite crystals are removed.
The novel process o~ this invention resides in using the exact forming solutions which have previously been taught for the preparation of zeolites such as ZSM-5 and adding therewith a buf~ering agent so as to have a final pH within the range of 9.5-12.5 depending on the particular crystal morphology which is desired~
The ~ollowing examples will illustrate the novel pxocess of this invention using various buffering agents. In all cases7 cQ110i~1 silica sol identified as Ludox LS containing 30 weight percent silica was used for cryst~11;7ations. The molar ratio of silica to tetrapropylammonium bromide (TPA8r) was held nearly constant 7~
at 19.8 to 19.9 and that of sodium hydroxide to TPABr ~as held ` constant at 3.05. Percent crystallinity is based on X ray comparison with a highly crystalline reference sample.
Generally, the reaction mixtures were prepared by dissolving tetrapropylammonium bromide, alkali hydroxide and a particular salt, water, and adding (Ludox ~silica sol to this solution.
All cryst~lli7~tions were carried out in non-stirred pressure vessels equipped with Teflo ~liners and heated by immersion in a constant temperature silicone oil bath~
~rief Description of the Figures Figures la and lb are scanning electron-micrographs of the product of Examples 3 and 4~ respectively.
Figures 2a, 2b, and 2c are scanning electron-micrographs of the product of Examples 6, 7, and ~ respectively.
S Fi9ure 3 is a scanning electron-micrograph of the product of Example 10.
Figures 4a, 4b, and ~c are scanning electron-micrographs nf the product of Examples 12, 13, and 14, respectively.
Figure 5 is a scanning electron-micrograph of the product of a o Example 15.
Figure 6 is a scanning electron-micrograph of the product of Example 16.
Figure 7 is a scanning electron-micrograph of the product of Example 17.
~s~ Figures 8a and 8b are scanning electron-micrographs of the products of Examples 19 and 20, respectivelyO
Figures 9a, 9b, and 9c are scanning electron~micrographs of the products of Examples 22, 23, and 24~ respectively~
Figure 10 is a scanning electron-micrograph of the product of 3 Example 25.
Figure 11 is a scanning electron-micrograph of the product of Example 27a.
Figure 12 is a scanning electron-micrograph of the product of Example 27b.
Figure 13 is a scanning electron-micrograph of the product of Example 27c.
Crys~11;7ation of High Silica ZSM-5 in the Presence of Phosphate As has been indicated previously, phosphate has been known to complex aluminum and its complexing and buffering properties cause cryst~lli7ation of zeulites with higher silica-to-alumina ratios than obtained from a similar phosphate-free reaction medium.
The reaction mixture of Example 1 was prepared using 4.2 mols of (NH4)2HP04 per mol of tetrapropylammonium bromide (TPABr) in an attempt to complex alumina impurities and buffer the sodium hydroxide added. The amount of buffer added was equivalent ko 0.42 equivalents of HPO-4 per equivalent of silica. The amount of (NH4)2HP04 was lowered in Examples 2 and 3 to amounts ranging from 0.21 to 0.14 equivalents per mol of silica, respectively.
Finally, am~onia was added in Example 4 to obtain an eqllirol~r concentration of (NH4)2HP04 and N~ . The eQuivalent amount of HPO 4 per mole of silica was 0.14. The reaction mixtures that crystallized completely had the hishest pH, the products having practically identical sorption capacities as will be shown in Table 1.
Cryst~11;7~tion of Hi~h Silica ZSM-5 in the Presenoe o~ Tartrate9 Citrate and Oxalate The reaction mixtures containing 2.1 mols of ammonium salts of tartaric, citric, and oxalic acid per mol of TPABr crystallized incompletely or not at all (Examples 5, 9 and 11). This amount is equivalent to 0.21 equivalents of tartrate and oxalate (Examples 5 and 11) and 0.32 equivalents of citrate (Example 9) per mol of silica.
Common to all ~hree is very low p~ of the f;nal solution. When the amount of tartaric acid was reduced, the crystallinity of the products improved. Simultaneously, the crystals became less elongated ~see - 8 ~ 5~37~
Figure 2). When only hal~ the amount of ammonium citrate was used (Example 10), citrate to TPABr equals 1.05, equivalents of citrate to moles of silica equals 0~16 which is similar to the reaction mixture o~ Example 6, and ayain, a good ZSM-5 was obtained. However, in the citrate mixture~ both the citric acid and ammonia were deereased, thereby the pH ~or Figure 2b was higher than that ~or Figure 3~
When the amount of ammonium oxalate was reduced (Examples 12-13), the resulting products were similar to those obtained with tartrate, i.e., see Table 2 and Figure 4~ Sodium oxalate, instead o~
ammonium oxalate, was used in Example 1~ resulting in a higher pH and more crys~ll77ation of quartz~ Results are shown in Table 2.
Cryst~ ation of High Silica ZSM 5 in the Presence of Gluconate~ Salicylate and EDTA
Reaction mixtures were prepared containing 2.1 moles of gluconate or salicylate per mol of TPABr which is equivalent to .105 equivalents o~ bu~fer per mol of silica, and these had pH values above 11 attributable to the weaker acids. The gluconate (Fxample 15) ~Pc~rosed during crys~lli7ation, and the carbon formed was burned of~ by calcination at 550C be~ore analytical tests were carried out.
The crystals obtained with gluconate are highly twinned (see Figure 5).
Less twinning is observed in the product of Example 16 obtained in the presence of salicylic acid (see Figure 6) Crystals similar to those obtained when phosphate was present in the reaction mixtures, i.e., see Figure 1, crystallized in the presence o~ ethylenediaminetetraacetate (EDTA~ (Figures 7a and b~
~ultiple twinning resulting in rudimentary spherulites can also be seen in Figure 7b. The material has a high crystallinity which is also evident from the high n-hexane and low cyclohexane sorp~ion capacitiesO See Table 3.
-~ 9~ s~
EXQMPLES 18~25 Crystallization in the Presence of Acetate and Carbonate Ammonium acetate was used in Examples 18-21. With 4.2 moles of acetate/mole of TPABr which is equivalent to ~21 equivalents of buffer per mol of silica9 th crystallization was still incomplete after 495 hours. With less ammonium acetate, 3.2 moles/mol of TPAer (Q.16 equivalents per mol of SiO2), somewhat more rapid crystallization was observed, although it was still incomplete a~ter 163 hours (see Example 19). The scanning electron micrograph shows the same rod-shaped crystals as observed previously from low pH
reaction mixtures, e.g., with tartrate (see Example 6, Figure 2a) and oxalate (Example 12, Figure 4a) At 2.1 moles of ammonium acetate/mole o~ TPABr (~105 equivalents of ammonium acetate per mole of SiO20), a well crystallized product was obtained in 65 hours (Example 20). The ratio of width/length of these crystals is considerably incre~sed, and some 90 twinning is observed (see Figure 8b). When the amount of NaOH wzs reduced (see Example 21), a material similar to that of Example 19 (Figure 8a) was obtained~
~mmonium carbonate was used in the remaining examples of Table 4 (Examples 2~25). At 3.2 moles of ammonium carbonate per mole of TPABr (0.16 equivalents of HC03 per mole o~ silica), rod-shaped crystals were obtained simultaneously with more stubby and 90 twinned crystals (see Figure 9a). Surface etching, caused by redissolution and beginning recrystallization indicates that the cryst~lli7ation was completed considerab~y sooner than after 122 hours when the reaction was terminated.
Considerably shorter crystals formed at carbonate/TPABr of
2.1 (Figure 9b) and at 1.05 (Figure 9c)(.105 and .055 equivalents of 3n bicarbonate per mole of silica)~ Although the latter product (Example 24) had good sorptive properties, beginning redissolution and deposition of quartz crystals caused by the long time at 200C9 is evident in Figure 9c.
Very large, hi~hly twinned crystals, about 40 x 70 Angstrom units (10 10m) in size, were obtained when the ratio of NaOHJTPABr was lowered to 2 (see Example 25~ Table 4~ and Figure 10). The final pH of this reaction mixture was about the same as the initial pH.
Results are shown in Table 4.
Example 1 2 3 4 Mol/mol o~ TPABr (NH4)2HPo4 4.2 2.1 1.4 1.4 NH40H _ __ ~_ 1.4 ~2 275 275 275 275 Initial pH 9~5 9.9 10.5 1007 Cryst~lli7ation Time9 Hrs. 128 1~8 65 65 Temp~g CC 200 200 200 200 Final pH 9.~ 9.5 10.1 N.A.
Identi~ication Amor. ZSM~5 ZSM-5 ZSM-5 Cryst. % ~0 95 85 Sorption, q/100~
Cyclohexane, (2666 Pa) 1.3 0.6 0.6 n-C6H14, (2666 Pa) 7 7 1007 10.7 H20, (1600 Pa) 1.2 1.4 1.5 Composition of Product Si02, wt. % 89.3 86.6 87.1 A123' ppm 450 440 ~0 Na, wt. ~ 0.02 0~08 0.08 N, wt. % 0.73 0.89 0.82 P, wt. % n.oo3 O.
Ash, wt. ~ 91.1 88.8 88.9 SiO2~A1203 (molar) 3374 3346 3085 SEM Fig. la lb TA~UE 2 Example 5 6 7 8 g 10 11 12 13 14 Moles/~ole of TPABr Tartaric Acid 2.11.58 1.05 0.7 Citric Acid -- -- -- -- 2.1 1.05 --( NH4) 2C24 __ _ - _ 2.1 1.59 1.05 __ N~2C24 -- -- -- -- -- __ __ __ __ O.7 NH40H 4.2 4.2 4.2 4~2 6.4 3.2 -- -~H20 286 286 286 286 267 260 310 310 310 31a Initial pH 9.810.4 11.7 12.6 9.2 lQ.35 9.6 10.011.35 13.1 Crystallization Time 9 Hrs . 168 166 57 91 72* 92 211 165 66 71 Temp. i C 200 200 200 200 200 200 200 200 200 2QO
Final pH 8.710.13 1006711.06 9.3810.16 N.A. 9.8310.76 11.74 X-Ray Identi~ication Amor.ZSM-5 ZSM-5ZSM-5~ ZSM-5+ ZSM-5 Amor. ZSM-5 ZSM-5 ZSM-5+
some Amor. ZSM-5 some Quartz Quartz Cryst. ~ 115 135 145 55 110 35 95 135 100 Sorption 5 q/lOOa Cyclohexane9 ~2666 Pa) 1.4 0.5 1.6 2.4 0.6 1.5 0.4 2.6 n-C6H14, (2666 Pa) 9.5 10.5 10.8 4.7 10.6 8.9 10.9 11.2 H20, ~1600 Pa3 0.7 2.9 5.1 1.9 1~3 0.7 2.8 6.4 Composltion or Product SiQ~, wt. % 86.5 84.4 86.1 86.7 87.0 83.~ 85.S
A1203, ppm 430 450 47Q 460 460 430 500 Na, wt. % 0.03 0.35 Q.59 0.06 0.02 0.33 0.84 ~, wt. ~ 0.~2 0.87 ~.78 0.92 0.79 0.85 0.76 Ash, wt. % 89.1 88.1 88.7 89.1 89.9 87.9 86.9 SiO?~A1203 (molar~ 3420 3188 3114 3204 3215 3301 2921 SEM Fig. 2a 2b 2c 3 4a 4b 4c * Followed by an additional heating at 180~C for 139 hours.
~L~L~S~7~L
Example 15 16 17 Moles~Mole of TPA~r Gluconic Acid 2.1 Salicylic Acid -~ 20 ~
EDTA ~~ ~- 0'7 NH40H 2.1 2.1 1.4 Initial pH 11.6 11.~ 10~3 Cryst~11;7ation Time, ~Irs. 67 48 67 Temp.~ C 200 200 200 Final pH 11.64 11.42 10 X-Ra~
Identification ~SM-5 ZSM~5 ZSM-5 Cryst. ~ 75 100 105 Sorption, ~/1009 Cyclohexane, (2666 Pa) 0.5 0.4 0.3 n-C6H14, (2666 Pa) 11.4 11.1 ll.o H20, (1600 Pa) 2.0 2.4 1.6 Composition o~ Prcduct SiO2, wt. % 96.7 ~.8 ~6.8 A1203, ppm 490 760 580 Na, wt. % 0.24 0.34 0.10 N, wt. % -- 0.81 0~69 Ash, wt. ~ 100* 89.2 88.8 SiO2/Al20~9 molar 3355 1942 2544 SEM Fig. 5 6 7 * calcined form Exploratory Cryst~ 7ations in the Presence of Anions Oonstanls~ SiO2/T M Br = 19.9, Temperature - 200 C
Example 18 19 20 21 22 23 24 25 Moles/Mole of TPABr NH4-Acetate 4.2 3.2 2.1 2.2 (NH4~2C3 ~ . 3.2 2.1 1.05 l.l NaOH 3.1 3.1 3.1 2.0 3.1 3.1 3.1 2.0 Initial p~ 9.80 10.~3 11.60 9.92 9.67 9.86 11.07 g.98 Cryst~lli7~tion Timet Hrs. 495 163 65 S62 122 64 165 72 Final pH 8.78 9~75 10.~1 9.73 10~1610.35 10.44 9.94 X-Ray Cryst., %(1~ 9O 95 140 100 110 155 130 85 Sorption~ ~100 Cyclohexane, ~2666 Pa) 0.7 Z.4 0.6 3O1 1~5 0~7 2~3 0~8 n-Hexane~ (2666 Pa~ 8.4 9.4 10.7 9.7 11.1 10.9 11.4 10.8 h'ater, ~1600 Pa) 0.2 0.8 2.8 0.2 1.9 3.5 4.1 0.1?
Composition of Product SiO27 wt. % N.A. 89.72~2~ 86.3 87.7 84.1 83.486.52(2~ 84.7 ~1203, ppm N.A. 430 445 460 44Q 495 430 480 Na, wt. % N.A. 0.05 0.37 0.05 0.24 0.48 0.57 0.30 6 N, wt. ~ N.A. 0.81 Q~89 0~87 0~82 1.18 0~75 0.81 Ash, wt. % N.A. ~9.8 88.6 89~0 87.8\86.5 87~3 88~4 SiO2~A1203, molar N.A. 3546 ~297 3241 3249 2864 3420 3000 SEM~ Fig. - 8a 8b -- 9a 9b 9c 10 ~1) All products were ZSM-5, no crystalline impurities were detected by x-ray diffraction (2) ~y difference ~ 15 ~
The ~ollowing examples demonstrate that the procedure can be applied to the crystallization of other zeolites as well. The pH at which buffering has to be acccmplished, however, will change from zeolite to zeclite.
Preparation of ZSM-ll A reaction mixture was prepared having the composition listed in the following table. Crystallization conditions7 sorption, a product analysis are also listed.
~ 16~ 37 Mol/Mol TBA~ (tetrabut~lammonium bromide) tNH4)2HPO4 0.74 NH40H 0.74 NaOH 3 9 Sio2 (as silica sol, 30%) 19.8 Initial pH 1~.89 Cryst~ tion Timeg Hrs. 140 lo Temperature, CC .140 Final pH 11.30 Identi~ication ZSM~ll Crystallinity 9 (rel. to reference sample) 145 Sorption, 9/1009 Cyclohexane, (2666 Pa) 2.5 n-Hexane, (2666 Pa) 8~6 Water, (1600 Pa) 205 Composition of Product sin2, wt. % 81.6 12 3~ ppm 410 Na, wt. % 102 N, wt. % 0.69 P, wt~ % .
Ash, wt. % 83.3 SiO~/A1203, molar 3383 ~ 17 ~ L
EX~MPLE 27 Preparation of ZSM-12 A reaction mixture was prepared having the composition listed in the Following table. C~ystallization conditions9 sorption, and product analysis are also listed.
Mol/Mol MTEACl (methyltriethylammonium chloride) a b c ~ 4 0.27 (CûOH)2 __ 0.14 --EDTA ~ 0.06 NaOH 0.42 0.50 0,50 SiO~ (as silica sol; 30%)1.63 1.63 1.63 Inital pH 12.52 13.00 12.97 Cryst~ atiom Time 3 hrs. 185 162 228 Temperature 9 ~C 160 160 150 Final pH 11.41 11.31 11.41 X-RaY
Identi~ication ZSM-12 ZSM-12 ZSM-12 Crystallinity, % ao llo llo Soprtion, ~/100~
Cyclohexane, (2S66 Pa) 7~3 7.8 8.1 n,Hexane, (2666 Pa) 7.8 6.5 6.5 water, (1600 Pa) 4.2 5.0 2.1 Chemical Composition SiO2, wt. % 88~5 89.3 ~9.0 2 3~ ppm 580 595 495 Na20, wt. % 0.50 0.26 0.24 N, wt. % 0.91 o.a4 1u05 Ashj w~. % 90.k 91.2 91.3 SiO2/A1203~ Molar 2594 2551 3058 SEM Fig. 11 12 13
Very large, hi~hly twinned crystals, about 40 x 70 Angstrom units (10 10m) in size, were obtained when the ratio of NaOHJTPABr was lowered to 2 (see Example 25~ Table 4~ and Figure 10). The final pH of this reaction mixture was about the same as the initial pH.
Results are shown in Table 4.
Example 1 2 3 4 Mol/mol o~ TPABr (NH4)2HPo4 4.2 2.1 1.4 1.4 NH40H _ __ ~_ 1.4 ~2 275 275 275 275 Initial pH 9~5 9.9 10.5 1007 Cryst~lli7ation Time9 Hrs. 128 1~8 65 65 Temp~g CC 200 200 200 200 Final pH 9.~ 9.5 10.1 N.A.
Identi~ication Amor. ZSM~5 ZSM-5 ZSM-5 Cryst. % ~0 95 85 Sorption, q/100~
Cyclohexane, (2666 Pa) 1.3 0.6 0.6 n-C6H14, (2666 Pa) 7 7 1007 10.7 H20, (1600 Pa) 1.2 1.4 1.5 Composition of Product Si02, wt. % 89.3 86.6 87.1 A123' ppm 450 440 ~0 Na, wt. ~ 0.02 0~08 0.08 N, wt. % 0.73 0.89 0.82 P, wt. % n.oo3 O.
Ash, wt. ~ 91.1 88.8 88.9 SiO2~A1203 (molar) 3374 3346 3085 SEM Fig. la lb TA~UE 2 Example 5 6 7 8 g 10 11 12 13 14 Moles/~ole of TPABr Tartaric Acid 2.11.58 1.05 0.7 Citric Acid -- -- -- -- 2.1 1.05 --( NH4) 2C24 __ _ - _ 2.1 1.59 1.05 __ N~2C24 -- -- -- -- -- __ __ __ __ O.7 NH40H 4.2 4.2 4.2 4~2 6.4 3.2 -- -~H20 286 286 286 286 267 260 310 310 310 31a Initial pH 9.810.4 11.7 12.6 9.2 lQ.35 9.6 10.011.35 13.1 Crystallization Time 9 Hrs . 168 166 57 91 72* 92 211 165 66 71 Temp. i C 200 200 200 200 200 200 200 200 200 2QO
Final pH 8.710.13 1006711.06 9.3810.16 N.A. 9.8310.76 11.74 X-Ray Identi~ication Amor.ZSM-5 ZSM-5ZSM-5~ ZSM-5+ ZSM-5 Amor. ZSM-5 ZSM-5 ZSM-5+
some Amor. ZSM-5 some Quartz Quartz Cryst. ~ 115 135 145 55 110 35 95 135 100 Sorption 5 q/lOOa Cyclohexane9 ~2666 Pa) 1.4 0.5 1.6 2.4 0.6 1.5 0.4 2.6 n-C6H14, (2666 Pa) 9.5 10.5 10.8 4.7 10.6 8.9 10.9 11.2 H20, ~1600 Pa3 0.7 2.9 5.1 1.9 1~3 0.7 2.8 6.4 Composltion or Product SiQ~, wt. % 86.5 84.4 86.1 86.7 87.0 83.~ 85.S
A1203, ppm 430 450 47Q 460 460 430 500 Na, wt. % 0.03 0.35 Q.59 0.06 0.02 0.33 0.84 ~, wt. ~ 0.~2 0.87 ~.78 0.92 0.79 0.85 0.76 Ash, wt. % 89.1 88.1 88.7 89.1 89.9 87.9 86.9 SiO?~A1203 (molar~ 3420 3188 3114 3204 3215 3301 2921 SEM Fig. 2a 2b 2c 3 4a 4b 4c * Followed by an additional heating at 180~C for 139 hours.
~L~L~S~7~L
Example 15 16 17 Moles~Mole of TPA~r Gluconic Acid 2.1 Salicylic Acid -~ 20 ~
EDTA ~~ ~- 0'7 NH40H 2.1 2.1 1.4 Initial pH 11.6 11.~ 10~3 Cryst~11;7ation Time, ~Irs. 67 48 67 Temp.~ C 200 200 200 Final pH 11.64 11.42 10 X-Ra~
Identification ~SM-5 ZSM~5 ZSM-5 Cryst. ~ 75 100 105 Sorption, ~/1009 Cyclohexane, (2666 Pa) 0.5 0.4 0.3 n-C6H14, (2666 Pa) 11.4 11.1 ll.o H20, (1600 Pa) 2.0 2.4 1.6 Composition o~ Prcduct SiO2, wt. % 96.7 ~.8 ~6.8 A1203, ppm 490 760 580 Na, wt. % 0.24 0.34 0.10 N, wt. % -- 0.81 0~69 Ash, wt. ~ 100* 89.2 88.8 SiO2/Al20~9 molar 3355 1942 2544 SEM Fig. 5 6 7 * calcined form Exploratory Cryst~ 7ations in the Presence of Anions Oonstanls~ SiO2/T M Br = 19.9, Temperature - 200 C
Example 18 19 20 21 22 23 24 25 Moles/Mole of TPABr NH4-Acetate 4.2 3.2 2.1 2.2 (NH4~2C3 ~ . 3.2 2.1 1.05 l.l NaOH 3.1 3.1 3.1 2.0 3.1 3.1 3.1 2.0 Initial p~ 9.80 10.~3 11.60 9.92 9.67 9.86 11.07 g.98 Cryst~lli7~tion Timet Hrs. 495 163 65 S62 122 64 165 72 Final pH 8.78 9~75 10.~1 9.73 10~1610.35 10.44 9.94 X-Ray Cryst., %(1~ 9O 95 140 100 110 155 130 85 Sorption~ ~100 Cyclohexane, ~2666 Pa) 0.7 Z.4 0.6 3O1 1~5 0~7 2~3 0~8 n-Hexane~ (2666 Pa~ 8.4 9.4 10.7 9.7 11.1 10.9 11.4 10.8 h'ater, ~1600 Pa) 0.2 0.8 2.8 0.2 1.9 3.5 4.1 0.1?
Composition of Product SiO27 wt. % N.A. 89.72~2~ 86.3 87.7 84.1 83.486.52(2~ 84.7 ~1203, ppm N.A. 430 445 460 44Q 495 430 480 Na, wt. % N.A. 0.05 0.37 0.05 0.24 0.48 0.57 0.30 6 N, wt. ~ N.A. 0.81 Q~89 0~87 0~82 1.18 0~75 0.81 Ash, wt. % N.A. ~9.8 88.6 89~0 87.8\86.5 87~3 88~4 SiO2~A1203, molar N.A. 3546 ~297 3241 3249 2864 3420 3000 SEM~ Fig. - 8a 8b -- 9a 9b 9c 10 ~1) All products were ZSM-5, no crystalline impurities were detected by x-ray diffraction (2) ~y difference ~ 15 ~
The ~ollowing examples demonstrate that the procedure can be applied to the crystallization of other zeolites as well. The pH at which buffering has to be acccmplished, however, will change from zeolite to zeclite.
Preparation of ZSM-ll A reaction mixture was prepared having the composition listed in the following table. Crystallization conditions7 sorption, a product analysis are also listed.
~ 16~ 37 Mol/Mol TBA~ (tetrabut~lammonium bromide) tNH4)2HPO4 0.74 NH40H 0.74 NaOH 3 9 Sio2 (as silica sol, 30%) 19.8 Initial pH 1~.89 Cryst~ tion Timeg Hrs. 140 lo Temperature, CC .140 Final pH 11.30 Identi~ication ZSM~ll Crystallinity 9 (rel. to reference sample) 145 Sorption, 9/1009 Cyclohexane, (2666 Pa) 2.5 n-Hexane, (2666 Pa) 8~6 Water, (1600 Pa) 205 Composition of Product sin2, wt. % 81.6 12 3~ ppm 410 Na, wt. % 102 N, wt. % 0.69 P, wt~ % .
Ash, wt. % 83.3 SiO~/A1203, molar 3383 ~ 17 ~ L
EX~MPLE 27 Preparation of ZSM-12 A reaction mixture was prepared having the composition listed in the Following table. C~ystallization conditions9 sorption, and product analysis are also listed.
Mol/Mol MTEACl (methyltriethylammonium chloride) a b c ~ 4 0.27 (CûOH)2 __ 0.14 --EDTA ~ 0.06 NaOH 0.42 0.50 0,50 SiO~ (as silica sol; 30%)1.63 1.63 1.63 Inital pH 12.52 13.00 12.97 Cryst~ atiom Time 3 hrs. 185 162 228 Temperature 9 ~C 160 160 150 Final pH 11.41 11.31 11.41 X-RaY
Identi~ication ZSM-12 ZSM-12 ZSM-12 Crystallinity, % ao llo llo Soprtion, ~/100~
Cyclohexane, (2S66 Pa) 7~3 7.8 8.1 n,Hexane, (2666 Pa) 7.8 6.5 6.5 water, (1600 Pa) 4.2 5.0 2.1 Chemical Composition SiO2, wt. % 88~5 89.3 ~9.0 2 3~ ppm 580 595 495 Na20, wt. % 0.50 0.26 0.24 N, wt. % 0.91 o.a4 1u05 Ashj w~. % 90.k 91.2 91.3 SiO2/A1203~ Molar 2594 2551 3058 SEM Fig. 11 12 13
Claims (7)
1. A process for producing high silica zeolites with control of the morphology of the zeolites so produced, which process comprises A) forming a reaction mixture containing a source of alkali metal oxide, a source of silica, a quaternary ammonium ion, water and a buffer capable of controlling the final pH of the reaction mixture to a value within the range of 9.5 to 12; and B) holding said reaction mixture at elevated temperature and pressure until zeolite crystals are formed.
2. The process of Claim 1 wherein the high silica zeolite is a ZSM-5 type zeolite.
3. The process of Claim 2 wherein the final is controlled within a range of 12-12.5 so as to obtain near spherulitic morphology.
4. The process of Claim 2 wherein the final pH
is controlled within a range of 10-10.5 in order to obtain rod-shaped ZSM-5 type crystals.
is controlled within a range of 10-10.5 in order to obtain rod-shaped ZSM-5 type crystals.
5. The process of Claim 1, 2 or 3 wherein the buffer is selected from the group consisting of phosphate, tartrate, citrate, oxalate, ethylenediaminetetraacetate, acetate and carbonate.
6. The process of Claim 2, 3 or 4 wherein the zeolite is ZSM-5.
7. The process of Claim 2, 3 or 4 wherein the zeolite is ZSM-12.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US37287282A | 1982-04-29 | 1982-04-29 | |
| US372,872 | 1982-04-29 |
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| Publication Number | Publication Date |
|---|---|
| CA1195971A true CA1195971A (en) | 1985-10-29 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000426581A Expired CA1195971A (en) | 1982-04-29 | 1983-04-25 | Method of preparing high silica zeolites with control of zeolite morphology |
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|---|---|
| EP (1) | EP0093519B2 (en) |
| JP (1) | JPS5913621A (en) |
| AU (1) | AU559968B2 (en) |
| BR (1) | BR8302202A (en) |
| CA (1) | CA1195971A (en) |
| DE (1) | DE3360656D1 (en) |
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|---|---|---|---|---|
| US4537758A (en) * | 1979-03-21 | 1985-08-27 | Mobil Oil Corporation | Process for preparing highly siliceous porous ZSM-12 type crystalline material |
| JPS5973427A (en) * | 1982-10-16 | 1984-04-25 | Res Assoc Petroleum Alternat Dev<Rapad> | Novel zeolite and preparation thereof |
| CA1209121A (en) * | 1983-07-12 | 1986-08-05 | Guenter H. Kuehl | Preparation of zeolite zsm-12 |
| US4497786A (en) * | 1983-07-27 | 1985-02-05 | Mobil Oil Corporation | Deagglomeration of porous siliceous crystalline materials |
| US4680170A (en) * | 1984-04-10 | 1987-07-14 | Imperial Chemical Industries Plc | Synthesis of zeolitic materials using ion-exchange resin |
| FR2564451B1 (en) * | 1984-05-18 | 1986-11-14 | Raffinage Cie Francaise | NOVEL CRYSTALLIZED MICROPOROUS SILICA, PREPARATION METHOD THEREOF AND APPLICATIONS THEREOF |
| US4851605A (en) * | 1984-07-13 | 1989-07-25 | Exxon Research & Engineering Co. | Process for synthesizing a zeolite catalyst on a pH controlled sodium free basis |
| US4764356A (en) * | 1984-12-21 | 1988-08-16 | Exxon Research & Engineering Co. | Process for synthesizing a zeolite catalyst on a pH controlled basis to improve catalyst life |
| JPS61242901A (en) * | 1985-04-17 | 1986-10-29 | Toyo Soda Mfg Co Ltd | Adsorbent for recovering bromine and method for recovering bromine |
| JPS61290148A (en) * | 1985-06-18 | 1986-12-20 | ミルトン ロ−ゼン | Building panel |
| US4853202A (en) * | 1987-09-08 | 1989-08-01 | Engelhard Corporation | Large-pored crystalline titanium molecular sieve zeolites |
| US4797267A (en) * | 1987-12-23 | 1989-01-10 | Mobil Oil Corporation | Method of producing rod-shaped ZSM-5 zeolite |
| CA1328099C (en) * | 1988-12-06 | 1994-03-29 | Steven M. Kuznicki | Small-pored crystalline titanium molecular sieve zeolites |
| JPH0356853U (en) * | 1989-10-05 | 1991-05-31 | ||
| ZA933879B (en) * | 1992-06-05 | 1993-12-27 | Exxon Chemical Patents Inc | ZSM-5-zeolite |
| DE4323774A1 (en) * | 1993-07-15 | 1995-02-09 | Basf Ag | Hollow ball-like agglomerated pentasil zeolites |
| DE69426907T2 (en) * | 1993-08-11 | 2001-09-27 | Mitsubishi Gas Chemical Co | Titanosilicate catalyst particles |
| US5876690A (en) * | 1997-02-11 | 1999-03-02 | National Science Council | Mesoporous aluminosilicate molecular sieves having "tubules-within-a-tubule" hierarchical order morphology and the preparation thereof |
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| GB2459067B (en) | 2007-03-16 | 2011-11-30 | Halliburton Energy Serv Inc | Robust inversion systems and methods for azimuthally sensitive resistivity logging tools |
| CA2680869C (en) | 2008-01-18 | 2011-07-12 | Halliburton Energy Services, Inc. | Em-guided drilling relative to an existing borehole |
| JP5990594B2 (en) * | 2011-12-01 | 2016-09-14 | エクソンモービル リサーチ アンド エンジニアリング カンパニーＥｘｘｏｎ Ｒｅｓｅａｒｃｈ Ａｎｄ Ｅｎｇｉｎｅｅｒｉｎｇ Ｃｏｍｐａｎｙ | Synthesis of highly active large crystal ZSM-5 |
Family Cites Families (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3386801A (en) | 1966-02-01 | 1968-06-04 | Mobil Oil Corp | Alkalimetal and alkylammonium phosphatoaluminate complexes and the preparation of crystalline aluminosilicates |
| US3702886A (en) | 1969-10-10 | 1972-11-14 | Mobil Oil Corp | Crystalline zeolite zsm-5 and method of preparing the same |
| US3709979A (en) | 1970-04-23 | 1973-01-09 | Mobil Oil Corp | Crystalline zeolite zsm-11 |
| US3832449A (en) | 1971-03-18 | 1974-08-27 | Mobil Oil Corp | Crystalline zeolite zsm{14 12 |
| US3949059A (en) | 1971-05-04 | 1976-04-06 | W. R. Grace & Co. | Process for producing faujasitic-type crystalline zeolites |
| GB1443707A (en) | 1972-10-30 | 1976-07-21 | Nat Res Dev | Decompression meter |
| US4016245A (en) | 1973-09-04 | 1977-04-05 | Mobil Oil Corporation | Crystalline zeolite and method of preparing same |
| US3941871A (en) | 1973-11-02 | 1976-03-02 | Mobil Oil Corporation | Crystalline silicates and method of preparing the same |
| US4046859A (en) | 1974-11-29 | 1977-09-06 | Mobil Oil Corporation | Crystalline zeolite and method of preparing same |
| US4041135A (en) * | 1975-07-25 | 1977-08-09 | J. M. Huber Corporation | Production of high capacity inorganic crystalline base exchange materials |
| US4061724A (en) | 1975-09-22 | 1977-12-06 | Union Carbide Corporation | Crystalline silica |
| US4088605A (en) | 1976-09-24 | 1978-05-09 | Mobil Oil Corporation | ZSM-5 containing aluminum-free shells on its surface |
| US4073865A (en) | 1976-09-27 | 1978-02-14 | Union Carbide Corporation | Silica polymorph and process for preparing same |
| US4104294A (en) | 1977-11-10 | 1978-08-01 | Union Carbide Corporation | Crystalline silicates and method for preparing same |
| US4204869A (en) | 1978-04-04 | 1980-05-27 | Polaroid Corporation | Method for forming noble metal silver precipitating nuclei |
| US4375573A (en) | 1979-08-03 | 1983-03-01 | Mobil Oil Corporation | Selective production and reaction of p-Disubstituted aromatics over zeolite ZSM-48 |
| ZA803365B (en) * | 1979-10-09 | 1981-05-27 | Mobil Oil Corp | Synthesis of large crystal zeolite zsm-5 |
-
1983
- 1983-04-08 AU AU13274/83A patent/AU559968B2/en not_active Ceased
- 1983-04-13 DE DE8383302066T patent/DE3360656D1/en not_active Expired
- 1983-04-13 EP EP83302066A patent/EP0093519B2/en not_active Expired - Lifetime
- 1983-04-13 ZA ZA832603A patent/ZA832603B/en unknown
- 1983-04-21 JP JP58069275A patent/JPS5913621A/en active Granted
- 1983-04-25 CA CA000426581A patent/CA1195971A/en not_active Expired
- 1983-04-28 DK DK190283A patent/DK160414C/en not_active IP Right Cessation
- 1983-04-28 BR BR8302202A patent/BR8302202A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| DK190283D0 (en) | 1983-04-28 |
| DK160414C (en) | 1991-08-19 |
| EP0093519A1 (en) | 1983-11-09 |
| ZA832603B (en) | 1984-11-28 |
| JPS5913621A (en) | 1984-01-24 |
| BR8302202A (en) | 1984-01-03 |
| AU559968B2 (en) | 1987-03-26 |
| DK160414B (en) | 1991-03-11 |
| EP0093519B2 (en) | 1990-10-31 |
| EP0093519B1 (en) | 1985-08-28 |
| JPH0250046B2 (en) | 1990-11-01 |
| DK190283A (en) | 1983-10-30 |
| AU1327483A (en) | 1983-11-03 |
| DE3360656D1 (en) | 1985-10-03 |
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